Following the successful demonstration in the summer of 2008 of how air conditioning load management resources could be used to provide spinning reserve through demand response, Southern California Edison (SCE) modified its Demand Response Spinning Reserve Pilot (DRSRP) to investigate the feasibility of bidding small, aggregated demand response from air conditioning as participating load (PL) according to requirements specified by the California Independent System Operator (CAISO). This 2009 SCE initiative, known as the Participating Load Pilot (PLP), was launched at the urging by CAISO that some PL be ready at the deployment of Market Redesign and Technology Upgrade (MRTU) Release 1.